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Biomedical subjects

P Thind

Publications and source records attributed to P Thind.

At least 19 recordsLinked to original sources
PubMed1997

Tamsulosin 0.4 mg once daily: tolerability in older and younger patients with lower urinary tract symptoms suggestive of benign prostatic obstruction (symptomatic BPH). The European Tamsulosin Study Group.

OBJECTIVES: To compare the safety and tolerability of tamsulosin 0.4 mg once daily in younger (< 65 years) and older (> or = 65 years) patients with lower urinary tract symptoms (LUTS) suggestive of benign prostatic obstruction (BPO). METHODS: In a retrospective analysis of two European double-blind, randomized, placebo-controlled trials, safety was assessed in 574 younger or older patients treated with tamsulosin or placebo for 12 weeks. RESULTS: The incidence of adverse events, drug-related adverse events, serious adverse events and discontinuations due to adverse events was similar in older and younger tamsulosin-treated patients and was not significantly different from placebo. Although abnormal ejaculation was slightly more common in younger than older men receiving tamsulosin, the difference was not statistically significant from the placebo groups in both age groups. The incidence of adverse events possibly associated with vasodilation in tamsulosin-treated younger and older patients was 8.4 and 4.2%, respectively; these were comparable with the values for placebo-treated patients: 7.5 and 6%, respectively. Baseline systolic blood pressure was higher in older than younger patients, but there were minimal changes in blood pressure or pulse rate in tamsulosin- or placebo-treated patients in either age group. CONCLUSIONS: Tamsulosin is well tolerated and suitable for use in older and younger patients with LUTS suggestive of BPO (symptomatic BPH).

Adrenergic alpha-Antagonists↗
PubMed1996

Influence of pudendal nerve blockade on stress relaxation in the female urethra.

The urethral pressure decay following a sudden and sustained dilatation corresponds to stress relaxation. Urethral stress relaxation can be described by the equation Pt = Pequ + P alpha e-t/tau alpha + P beta e-t/tau beta, where Pt is the pressure at time t, Pequ is the equilibrium pressure after dilatation, P alpha and P beta are pressure decay, and tau alpha and tau beta are time constants. The time constants have previously proved independent of the way the dilatation is performed. The urethral stress relaxation obtained in 10 healthy women before and after pudendal nerve blockade was analysed by the mathematical model and the pressure parameters and time constants determined. The fast time constant, tau beta, was reduced by the nerve blockade, whereas tau alpha was unaffected, however, both P alpha and P beta were reduced. No single stress relaxation parameter can therefore be related to the muscle or the connective tissue components. The method may prove useful in the further evaluation of the closure function of the urethra with special reference to the pathophysiology of stress urinary incontinence.

Adult↗
PubMed1995

Passive urethral resistance to dilation in healthy women: an experimental simulation of urine ingression in the resting urethra.

The dynamic urethral pressure response to a simulated urine ingression was studied at the bladder neck, in the high pressure zone, and in the distal urethra in 10 healthy female volunteers. The pressure response was characterised by a steep pressure increase simulataneous with the urethral dilation, followed by a decay during the next seconds until a new equilibrium pressure was reached. The pressure decay could be described by a double exponential function in the form Pt = Pequ + P alpha e-t/tau alpha + P beta e-t/tau beta, where Pt represents the pressure at the time t, Pequ represents the pressure at equilibrium, P alpha and P beta express the decline in pressure, and tau alpha and tau beta are time constants. The size of the pressure response proved highly dependent on velocity and size of dilation as well as urethral site of measurement, with the maximum values in the high pressure zone. The time constants, on the other hand, were uninfluenced by these factors. The pressure response represents an integrated stress response from the surrounding tissues which may reflect the visco-elastic properties of the structures involved. The findings indicate that striated muscle fibres are of dominating significance for the pressure response, and the varying size of the response along the urethra is in accordance with the localization of the horseshoe-shaped rhabdosphincter, which quantitatively is the dominating circularly arranged structure around the female urethra. Functionally, the stress response will oppose any dilation, and increasingly with rising size or velocity of dilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

The urethral resistance to rapid dilation: an analysis of the effect of autonomic receptor stimulation and blockade and of pudendal nerve blockade in healthy females.

The urethral closure function is based upon permanently as well as adjunctively acting closure forces during rest and stress episodes, respectively. During urine ingression intra- and peri-urethral structures are suddenly stretched resulting in a pressure response which strengthens the closure function by sustaining the resistance to dilatation of the urethra. A method for measurement of the resistance to rapid urethral dilatation was used to evaluate the influence of noradrenaline, prazosin, terbutaline, propranolol, carbachol, and atropine, as well as bilateral pudendal nerve blockades in 40 healthy women. The drugs caused no significant change in the urethral resistance to dilatation, whereas the pudendal blockade produced a significant (p < 0.05) reduction at the bladder neck and in the high pressure zone. Although a quantitative assessment of their contribution cannot be obtained from this study, it may be concluded that the striated muscles innervated by the pudendal nerve are of major importance for the urethral resistance to dilatation.

Adult↗
PubMed1994

Characterization of pressure changes in the lower urinary tract during coughing with special reference to the demands on the pressure recording equipment.

The exact demands on urodynamic equipment for measurement of coughs and cough associated pressure changes in the lower urinary tract have been analyzed from high-speed pressure recordings using a double microtip transducer and a storage oscilloscope. The equipment was tested in vitro by the step-test method. The natural frequency response was 175.6 Hz and the rise-time 2.5 ms, resulting in accurate measurements of frequencies up to about 60 Hz, which is way above the clinically measured frequencies. Four men and 2 women, all of whom were healthy volunteers, were examined in the supine position with an empty bladder. Pressures were measured in the bladder and in the external sphincter zone of the urethra. The spectral power density of the bladder and urethral pressures were calculated by Fourier analysis. The pressure changes in the urethra were in all volunteers equal to or slower than in the bladder. The analysis of the spectral power density showed that 99% of the pressure changes could be recorded with an instrument capable of recording 9 Hz frequencies, i.e., with a sampling rate of 18 Hz or more.

Adult↗
PubMed1994

The effect of pharmacological stimulation and blockade of autonomic receptors and of pudendal blockade on urethral stress relaxation in healthy women.

OBJECTIVE: To examine the influence of autonomic receptor stimulation and blockade (noradrenaline, prazosin, terbutaline, propranolol, carbachol and atropine), and of pudendal nerve blockade on urethral stress relaxation. SUBJECTS AND METHODS: Forty healthy women were evaluated. The stress relaxation parameter was defined as the relative rate of pressure decrease during a fixed period of time following a rapid dilatation of the urethra. The dilatation was performed by water-infusion into a small rubber cylinder placed in the urethra. RESULTS: The drugs did not affect stress relaxation significantly, whereas the pudendal blockade produced a significant change along the length of the urethra characterized by a faster pressure decay following dilatation. CONCLUSION: In women, stress relaxation in the urethra relies significantly on the pudendal nerve-innervated striated muscles.

Adult↗
PubMed1994

The effect of bilateral pudendal blockade on the adjunctive urethral closure forces in healthy females.

The effect of bilateral pudendal blockade on the urethral pressure and power generation during coughing and pelvic floor squeezing was evaluated in 10 healthy women. The measurements were carried out at the bladder neck, in the high pressure zone, and distally in the urethra before and after blockade. Strong adjunctive closure forces were demonstrated all along the urethra. They were significantly reduced by pudendal blockade except at the bladder neck during coughing. The results indicate that the pudendal innervated striated muscles contribute significantly to the adjunctively acting closure forces all along the female urethra, including the bladder neck. Some passive pressure transmission to the bladder neck seems to take place during stress episodes following pudendal blockade, but whether it occurs in healthy females remain uncertain. The findings following pudendal blockade, corroborate with those in stress incontinent women, and thereby support the concept that striated muscle weakness is of pathophysiological significance in stress urinary incontinence.

Adult↗
PubMed1993

The dynamic urethral sphincter function in healthy females assessed by rapid dilatations in the resting state: evaluation of reproducibility.

Recording the pressure response to rapid dilatations enables one to assess urethral sphincter function. The rapid dilatations of the urethra experimentally simulate the ingression of urine. A method that enables standardized dilatations of 2-mm long urethral segments was urine (USED).A method that enables standardized dilatations of 2-mm long urethral segments was used, and the subsequent pressure response was measured. The reproducibility of the urethral pressure response to rapid and standardized dilatations was evaluated by repeating the measurements after 1 week in 10 healthy females. The pressure response showed an acceptable reproducibility. The urethral pressure increase as a response to dilatation is considered to rely on stretching of intra- and periurethral fibers. Calculations of strain (change in length divided by the original length) of circularly arranged fibers when the urethra is dilated indicate that the tension (and pressure) bearing layers must be located outside a circular zone with a radius of 4 mm perpendicular to the longitudinal axis of the urethra.

Adult↗
PubMed1993

The dynamic pressure response to rapid dilatation of the resting urethra in healthy women: an in vivo evaluation of visco-elastic properties.

The urethral pressure response to a sudden forced dilatation was studied at the bladder neck, in the high-pressure zone and in the distal urethra in ten healthy female volunteers. The pressure response was fitted with a double exponential function of the form Pt = Pequ + P alpha e-t/tau alpha + P beta e-t/tau beta, where Pequ, P alpha and P beta are constants, and tau alpha and tau beta are time constants; this equation has previously been demonstrated to describe the pressure decay following dilatation. On the basis of a theoretical model the elastic and viscous constants for the urethral tissues were computed. The results showed significant differences along the urethra, with the high-pressure zone showing the highest maximum and equilibrium pressures, fastest pressure decay and highest elastic coefficient. The pressure response represents an integrated stress response from the surrounding structures, which reflects the visco-elastic properties of the tissues involved. The findings seem therefore to correlate well with the anatomical findings, which have shown a high fibre density of the horseshoe-shaped rhabdosphincter in the mid-portion of the urethra. The method permits a detailed assessment of static and dynamic urethral responses to dilatation which can be applied as an experimental simulation of urine ingression, and is therefore presumed to be of value in the evaluation of normal and pathological urethral sphincter function.

Adult↗
PubMed1993

In vivo evaluation of visco-elasticity in a biological tube. Part 1. Stress relaxation in the female urethra studied by cross-sectional area and pressure measurements.

The urethral response to a sudden forced dilatation was studied by a mathematical analysis of the pressure response in ten healthy women. A total of 60 dilatations, using various sizes and velocities of deformation, were performed in the high-pressure zone. The decay in pressure during relaxation proved to follow an exponential equation of the following form: Y = Z + C alpha e-t/tau alpha + C beta e-t/tau beta, where Z is the equilibrium pressure, C alpha and C beta are pressure decay, and T alpha and T beta are time constants. The time constants were unaffected by the circumstances of dilatation, whereas all the other parameters were correlated to size or velocity of dilatation, or both. The time constants showed a fairly high reproducibility when repeated after one weak. The method is presumed to characterise the tissue composition of the periluminal tissue layers and may prove useful in the evaluation of the normal urethral sphincter function. Furthermore, it may prove of value in the elucidation of the pathophysiology of stress urinary incontinence.

Adult↗
PubMed1993

In vivo evaluation of visco-elasticity in a biological tube. Part 2. Application of a mechanical model.

Based on a theoretical model, the urethral stress-relaxation response following a sudden forced dilatation was studied in ten healthy female volunteers. The energy dissipation following a sudden urethral dilatation proved to follow the function Y = Z + C alpha e-t/tau alpha + C beta e-t/tau beta. Hence, a mechanical model was chosen, consisting of two Maxwell elements and one Hooke element coupled in parallel. The decay in force following deformation may be described as F = F(o) exp (-t.E/eta) for each Maxwell element. Thus, it was possible to determine the elastic E and viscous eta coefficients for the participating mechanical equivalents in the model, and thereby quantitatively describe the visco-elastic properties in the urethra. The reproducibility of the elastic and the viscous coefficients proved to be fairly high, and they seemed to be unaffected by the size of dilatation. On the other hand, the rate of dilatation clearly influenced the computed parameters. However, this phenomenon was easily explained by the duration of the deformation, which allowed the viscous elements to move before any measurements were performed. The present method permits in vivo evaluation of the elastic and viscous properties of the urethra, as well as other accessible biological tubes, and may be of value in the description of normal physiological and pathophysiological behaviour of the structures studied.

Adult↗
PubMed1993

The influence of beta-adrenoceptor and muscarinic receptor agonists and antagonists on the static urethral closure function in healthy females.

The effects of terbutaline, propranolol, carbachol, and atropine on the static urethral closure function were investigated in 20 healthy women. Terbutaline caused a statistically reduction of the urethral pressure in the high pressure zone, but not at the bladder neck or in the distal urethra. The other drugs caused no significant pressure changes. None of the drugs used produced significant changes in the static viscoelastic properties, elastance, and hysteresis of the resting urethra. It is suggested that terbutaline partly reduces intraurethral pressure by reducing muscular tone in the rhabdosphincter and pelvic floor.

Adrenergic beta-Agonists↗
PubMed1993

The effect of pharmacological stimulation and blockade of autonomic receptors on the urethral pressure and power generation during coughing and squeezing of the pelvic floor in healthy females.

The effect of autonomic receptor agonists and antagonists on the urethral pressure and power generation during coughing and squeezing of the pelvic floor has been evaluated in 30 healthy females. The measurements were carried out at the bladder neck, in the high pressure zone, and distally in the urethra. The used drugs (noradrenaline, prazosin, terbutaline, propranolol, carbachol and atropine) caused no significant change in the pressure and power generation. The clinically relevant influence of drugs on the urethral closure function should be re-appraised when based on profilometry in the resting state. The results support that the effect of the autonomic nervous system on the urethral closure function is insignificant in healthy women. They furthermore indicate that investigations on the ability to secure continence cannot be based solely on resting pressure profilometry, but should be accomplished by measurements during stress episodes.

Adult↗
PubMed1992

Urethral pressure--which one?

Urethral pressure was investigated by a method which allowed simultaneous measurement of the cross-sectional area. In healthy women a pressure range of 25-140 cm H2O was recorded at one urethral site as a response to the circumstances under which the measurement was performed. The pressures obtained were related to the degree of urethral distension and to the time after the change in distension. Measuring urethral pressure at one specific degree of distension results in one specific pressure value according to the dimensions of the measuring probe. However, this specific pressure value cannot be considered to supply more information on urethral sphincter function than any other pressures included in a range which can be obtained by changing the circumstances under which the measurement are carried out. More provocative methods of pressure measurement which simulate some of the physiological conditions of the urethra may provide more information on sphincter efficiency.

Adult↗
PubMed1992

Pressure response to rapid dilation of resting urethra in healthy women.

Rapid urethral dilations were performed by a balloon mounted on a double-tip transducer catheter for simultaneous measurement of pressure in urethra and bladder. The cross sectional area of the urethra was measured according to the field gradient principle. Pressure and cross sectional area were recorded synchronously. The response of the female urethra to rapid dilation is a typical stress relaxation effect with a pressure peak followed by a pressure decay over a few seconds. The peak pressure response represents the bladder pressure required in producing a corresponding urethral dilation by the ingression of urine. The increase in pressure response was statistically significant by increasing rate as well as size of dilation. The method enables experimental simulation of stress urinary incontinence in vivo which may bring further insight into the physiology of the urethral closure function and the pathophysiology of stress incontinence. For comparative studies rapid dilation should be performed under standardized circumstances.

Adult↗
PubMed1992

Stress relaxation phenomenon in the healthy female urethra.

Following dilatation, urethral pressure declines over the next few seconds to a state of equilibrium. The stress relaxation parameter, Pt0.5, was defined as the relative pressure decrease 0.5 s after dilatation, where the pressures at 0.1 s and at the new equilibrium were set to 100% and 0% respectively. Pt0.5 was calculated from 171 urethral dilatations performed at each of 3 urethral sites of measurement in 10 healthy volunteers. It was found to be independent of the rate and size of urethral dilatation. It showed a fairly high reproducibility rate when repeated after 1 h and 1 week. Pt0.5 was calculated to approximately 60% with no variation along the urethra. The parameter is assumed to be useful in evaluating urethral sphincter function. Although the method can be performed without special urodynamic equipment, the frequency response of the pressure measurement system must be adequate.

Adult↗
PubMed1992

Urethral stress relaxation phenomenon in healthy and stress incontinent women.

Urethral stress relaxation was induced by sudden forced dilatation. The stress relaxation parameter, Pt0.5, was defined as the relative pressure decrease 0.5 s after dilatation, where the pressures at 0.1 s and at the new equilibrium were set to 100% and 0% respectively. Pt0.5 was calculated in 28 healthy and 30 women with genuine stress incontinence. Measurements were performed at the bladder neck, in the high pressure zone and in the distal urethra. The measurements showed that all along the urethra, Pt0.5 was statistically significantly greater in the healthy women than in the incontinent women, the greatest difference being found at the bladder neck. Although there was a slight overlap in values between the 2 groups, this parameter seems useful in differentiating between competent and incompetent urethral sphincters.

Adult↗